The present invention relates to a hole punching apparatus, and more particularly to a hole punch that automatically punches two or three holes in response to a user's selection.
Standard letter sized and legal sized papers used in businesses and homes throughout the world are often punched with two or three holes at predetermined locations along their edges in order to be placed into binders, folders, and other paper storage mediums having holes at locations corresponding to the holes of the papers. Conventionally, three holes may be punched along the longer edge of letter sized paper or two holes may be punched along the shorter edge of letter or legal sized paper.
Many hole-punching devices in use today are manual devices that can punch one or a plurality of holes through a single sheet or a sheaf of papers using a force that a user exerts on a lever, which in turn causes punch rods to pierce the paper at predetermined locations. To accommodate for differences in the desired number of holes, these manual devices require manual reconfiguration of the punches by a user, such as by unlocking the punches, then sliding the punches along a rail, and finally relocking the punches.
Some hole-punching devices incorporate an electric motor that may be activated by a selector switch. In such devices, the electric motor typically drives a rotational motion to a driveshaft and cams located therealong that interface with a cam surface on the punch rods, i.e., cam followers, thus providing leverage to the punch rods to pierce paper inserted into a guide of the punch.
Some more advanced electric hole-punching devices have also included switching mechanisms for punching different numbers of holes through the use of a selector. Such devices are described in U.S. Pat. No. 6,065,379 to Shinno et al. and U.S. Pat. No. 6,983,877 to Ko et al., the entire disclosures of which are hereby incorporated by reference herein. In these punching devices, the switching mechanisms typically include cams that are shifted from one position to another to change between a mode for punching two holes and a mode for punching three holes into paper inserted into these punching devices.
There exists a need, however, for providing simple switching between modes for punching different numbers of holes in sheets of paper.